Kidney stone disease is a substantial health problem associated with significant pain, suffering, and economic costs. 5% to 15% of the population will have a symptomatic episode of a stone by the age of 70 and at least 50% of these individuals will have recurrent disease. To date, the only well-defined genetic abnormalities leading to hyperoxaluria and calcium oxalate stone disease have been described for primary and secondary hyperoxaluria and associated with specific enzyme errors. However, the familial tendency of idiopathic calcium oxalate stone disease coupled with the common trend for stone recurrence have led to the speculation that many idiopathic calcium oxalate stone formers may have a genetic predisposition for their stone disease. We propose to explore the genetic linkages underlying idiopathic hyperoxaluria and calcium oxalate stone disease, utilizing and applying to stone disease the methods and genetic observations from existing animal models currently being used to explore the genetic basis of hypertension. The application of genomic methods to stone disease is new. The proposed studies will allow us to define the genetic linkages that mediate critical mechanistic events in idiopathic calcium oxalate stone disease including the initiation, progression, and physiologic consequences of hyperoxaluria, crystalluria, and calcium oxalate crystal retention. We will use available genomic rat resources to explore both the genetic linkages in calcium oxalate stone disease and the genetic linkages between calcium oxalate stone disease and hypertension. Three specific major breeding colonies will be used: 1) The Dahl SS rat that demonstrates salt sensitive hypertension, 2) A colony of Brown Norway rats that are about 62% consomic with the Dahl SS rat, and 3) Consomic strains of Dahl SS rats that have one chromosome at a time introgressed into the Dahl SS genetic background from the Brown Norway rat, creating a rat that is about 98% consomic with the parent Dahl rat. Our working hypothesis is that there are specific genetic linkages that are associated with idiopathic hyperoxaluria and calcium oxalate stone disease and that the pathophysiology of stone disease associated with hypertension is different from stone disease absent hypertension. There are three Specific Aims. Specific Aim I: To determine what the associative effect of hypertension and hyperoxaluria is on urine chemistry and how these associated challenges influence the potential for calcium oxalate stone disease. Specific Aim II: To define the specific tissue injury associated with hypertensive and with hyperoxaluric challenges and to correlate these findings with effective calcium oxalate crystal attachment and stone maturation. Specific Aim III: To identify the chromosomes that harbor genes that control major susceptibility and resistance to hyperoxaluria, calcium oxalate crystalluria, and stone disease using a chromosomal replacement panel of consomic Dahl SS rats.